Rack for electroplating



March 7, 1933. E. SOHN I RACK FOR ELECTROPLATING Filed Dec. 30, 1926 3Sheets-Sheet l ITXETTI E15 521027? John March 7, 1933. E. SOHN RACK FORELECTROPLATING Filed Ben. 30, 1926 5 Sheets-Sheet 2 LvE March 7, 1933.sol-IN 1,899,992

RACK FOR ELECTROPLATING Filed Dec. 30, 1926 s Shets-Sheet 5 &

Patented Mar. 7, 1933 EBWIN SOHN, OF OAK PARK, ILLINOIS RACK roannncrnornarme Application filed December 30, 1926. Serial'Rc. 157,919.

This invention relates to a rack for use in electroplatin In chromiumplating processes it is di cult to secure unlform current distribution,especially when plating irregularly shaped objects. To correct thissituation, use is made of what is hereinafter called booster current, aswill later be explained in connection with the description of thedrawings.

It is an object of this invention toprovide an improved rack for holdingarticles during electroplating.

Several modifications of my invention adapted for use in chromiumplating are illustrated in the drawings.

As shown on the drawings: Figure 1 is a top plan view of anelectroplating vat, with parts broken away and in section.

Figure 2 is a cross sectional View of the same.

Figure 3 is a fragmentary elevational view of a cathode rack.

Figure 4 is an enlarged sectional view taken substantially on line IV IVof Figure 2, and illustrating the method of suspending articles to beplated.

Figure 5 .is an enlarged sectional detail view.

Fi re 6 is an elevational view of a modified cm of cathode rack.

Figure 7 is an end view of the same.

Figure8 isan enlarged fragmentary view illustrating a method ofsuspending an article to be plated.

Figure 9 is an enlarged detail sectional view.

Figure 10 is an elevational view of a second modified form of rack.Figillllie 11 is a sectional view taken on line XI- of Figure 10.

Figure 12 is an enlarged detail sectional view, and v Fi re 13 is asectional view taken on line XII XIII of Figure 10. p

. As illustrated in Figures 1 and 2, the reference numeral 1 indicates atypical rectangular shaped vat-for carryin out the'electrodeposition ofchromium. node plates 2, preferably of ferrous metal, are adapted toover the bus bar 6. Said bar 7 is provided at spaced intervals with aplurality of spring clip members 9 on which articles 10 are adapted tobe suspended in the plating bath. Said clip members 9 comprise flatstrips of springy metal vsecured intermediate their ;ends to the rod 7and arranged on opposite sides thereof. The ends of each set of saidclips 9 diverge as at 11 for the purpose of securely engaging withinhollow articles,

such as 10, which are to be plated. Said article 10 represents a hollowcap having a threaded recess 16 and perforations 50 in the top thereof.Ordinarily it is very diflicult if not impossible to plate the surfaceof a perforated article or the inside of hollow articles with an evenand uniform plating or coating. I- have found however that if thecurrent strength is locally increased or-boosted in the locality ofthe-recess or hollow ortion that the plating may be very satis actorilyeffected. In this connection, a small rod 12 of ferrous metal isinserted in the bar 7 and insulated therefrom by means ofmica bushings13 and washers 14 and secured to said bar 7 by means of nuts 15. One ofsaid bars 12 is positioned between adjacent members of each set of clips9 and extends on each side of the bar 7 so as to project a shortdistance into the recess 16, in the article 10. Lead wires 17 connecteach of the rods 12 with one or the other of the anode bus bars 4, towhich said lead wires are secured by means of bands or clips 18. In thisway, the anode current is conducted toa point adjacent the recess 16 soas to boost the current strength locally at that point. As a result theinner-surface of hollow articles may be readily plated. Also the currentstrength is sufficiently increased M by this means in the locality ofthe perforations 50 to cause the surface to be plated to the very edgesof said perforations.

It will be understood that the articles to be plated are in electricalcontact through the clips 9 and the bar 7 with the cathode bus bar, andthat said articles form a part of the cathode. In order to preventexcessive loss of current from the surface of the bar 7 and clips 9,these surfaces are preferably coated with an insulating compound ofasphaltic nature or covered With a molten asphaltic base compound.

In Figures 6 to 9 inclusive there is shown a modified form of cathoderack 20 suspended from a cathode bus bar 21. Said rack 20 comprises apair of vertical end strips 22 joined by means of spaced parallelhorizontal bars 23. At spaced intervals along said bars 23 are securedpegs 24 on which articles 25 are adapted to be suspended for plating. Asshown, the article 25 is a bib or portion of a faucet having a threadedend 26 into which the peg 24 may be inserted. On account of the filletssuch as 27 in an article of this type, it is very difficult to secure aneven and uniform coating. Accordingly, booster current is supplied bymeans of a plurality of wires 28 of ferrous metal of suitable size andsuitably spaced, carrying anode current. Said wires 28 are suspendedbetween pivotal arms 29 carried by the end strips 22 but insulatedtherefrom by insulation 32 and 33. Each of said arms 29 is provided witha plurality of closely spaced holes 30, through which the wires 28 maybe passed. Lead wires 31 connect said arms 29 to the anode bus bar (notshown). It will be understood that the number of booster current wires28 used and their relative position to the article to be plated may bevaried to suit the particular conditions.

Where there is a large opening in the article to be plated, such as theopening 51 in the article 25, and it is desired to plate to the edge ofthe opening, it is necessary to plug the opening. as by means of a leadplug.

In Figures 10 to 13 inclusive there is shown a second modified form ofrack 34 adapted for use in plating certain types of articles, such asillustrated by the reference numeral 35. In this case the articles 35are secured to the vertical strips 36 of the rack 34 and spacedthereupon by means of split pegs 37 extending into holes 38 in said ar-1 titles Each of said articles 35, as shown,

comprises a curved flat strip having lugs 39 extending from one facethereof. It is preferable to stagger the articles 35 by spacing themvertically and placing them on alternate opposite sides of the strips 36with the lugs 39 extending inwardly. It is then possible by means ofbooster current wires 40 positioned at suitable points with respect tothe lugs 39 to obtain an even and uniform plating of chromium on boththe body portion of the articles 35 and on the fillet surfaces of thelugs 39. Said wires 40 are suitably suspended from cross bars 41 securedto the strips 36 and insulated therefrom by insulation 53. The ends ofsaid wires 40 may be threaded and provided with nuts 42, both the wireand nuts being in electrical contact with the cross bar 41. Lead wires44 connect said cross bar 41 to the anode current.

It is obvious that the type of apparatus used will vary with the natureof the work to be plated, but the various types shown in the drawingswill serve to illustrate the principle by which the surface of hollow orperforated articles and articles having irregular contours may besuccessfully chromium plated.

I am aware that many changes may be made and numerous details of theprocess and construction may be varied through a wide range withoutdeparting from the principles of this invention, and I therefore do notpurpose limiting the patent granted hereon, otherwise than necessitatedby the prior art.

I claim as my invention:

1. As a new article of manufacture, a rack for use in plating articlescomprising a bar, resilient means secured at intervals thereto andadapted to be inserted into the articles to be plated to maintain saidarticles thereon, auxiliary anodes in said bar adapted to project intothe articles to be plated, means for insulating the anodes from saidresilient means and means for partially insulating said anodes from anelectroplating solution.

2. As a new article of manufacture, a rack for use in plating irregulararticles comprising a bar, a plurality of spring strips mounted atintervals on said bar and adapted to project into the articles to beplated to maintainsaid articles thereon, anodes adjustably mounted insaid bar adjacent said spring strips whereby they may be properlypositioned with respect to the articles so as to control the currentdensity acting on said articles, means for insulating said spring stripsfrom said anodes, and means for connecting said spring strips to anegative current lead and said anodes to a positive lead.

3. As a. new article of manufacture, a rack for use in plating irregularobjects comprising a bar, bowed spring strips secured at intervals toopposite faces of the bar, the strips on one face opposing the strips onthe opposite face to form pairs, each pair of strips being adapted toresiliently support an article on an end thereof, an anode arranged insaid bar between the springs of each pair of strips with an end thereofadjacent the article on said strips, means for insulating said anodesfrom said spring strips, and means for connecting the spring strips ascathodes.

4. A device as in claim 3 wherein the spring strips and anodes aresecured to the bar adjacent the midpoints of the same whereb an articlemay be supported and plated on th ends of the spring strips. 5.Apparatus for plating irregular shaped articles with metals fromsolutions of low throwing power comprising a plating tank, anodestherein, a plating rack ad acent said anodes, said rack comprising a barsupported at its end in said tank, spring strips in pairs secured tosaid bar, each pair being constructed to resiliently maintain an articleon an end thereof, an anode situated in said bar between the membersofeach pair of springs with an end thereof positioned in proximity tothe irre lar surface of an article, means for insulatlng said anodesfromsaid springs, and means for electrically connecting said springs ascathodes and said second anodes to a positive source of current.

6. A device as in claim 2 wherein each pair of springs and each anodeare secured to the rack bar adjacent their respective midpoints wherebyan article may be supported and plated on both ends of a pair ofsprings.

In testimony whereof I have hereunto subscribed my name.

ERWIN SOHN.

